BNYZWOT RC33 NC Recessed Wired Security Window Door Contact Sensor Alarm Magnetic Reed Switch White 10 Pair

Description: 1.NC means Normally Closed:When the magnet together, the circuit is conductive( light on ); when the magnet separate, the circuit is not conductive ( light off ). When make order,pls check carefully! 2.These are the door contact sensors that are in use with any and all commercial or residential card access systems as well as all security burglar alarm system. 3.Work as an anti-theft alarm, ideal for metal door and window.